Every year, thousands of workers are subject to burns and other injuries due to arc flash events. Arc flashes occur when an electric current passes through an air gap between electrified conductors, or from conductor to ground, when the insulation or isolation is not sufficient to withstand the applied voltage. While the arc flash event itself can occur almost immediately, or within a few milliseconds, the results can be lasting, ranging from superficial burns to debilitating injury, or even death.
Due to the significant threats posed by arc flash events, professional and trade associations including the Institute for Electrical and Electronics Engineers (IEEE) and the National Fire Protection Association (NFPA) have conducted substantial research and testing to quantify and improve related electrical safety standards. In particular, these efforts are directed to predicting the hazards associated with arc faults and the accompanying arc blasts, in order to provide practical workplace safeguards.
The most effective way to protect workers from arc flash hazards is to de-energize the circuit before attempting to work on or near the exposed conductors. There are some tasks, however, for which work must be performed on energized components, including troubleshooting, testing, and certain types of repair.
When work is necessary on an electrified system, an electrical hazard analysis must be conducted. In general, this includes not only a shock hazard analysis to determine the voltages to which personnel may be exposed, but also an arc flash hazard calculation. The arc flash analysis determines the arc flash protection boundary (or arc flash boundary), from which non-essential workers and other personnel should be excluded. The arc flash analysis can also be used to classify the arc flash risk and determine what personal protective equipment (PPE) may be required, for those personnel who must work inside this boundary.
To address these issues, arc flash hazard analysis is utilized to model arcing currents and incident energy exposure levels to which workers may be exposed in a potential arc flash event. The arc flash protection boundary is also calculated, so that appropriate protective measures can be taken.
Arc flash analysis, however, is a highly complex task, requiring an extensive understanding of electronics, electromagnetic effects, plasma flow properties and magnetohydrodynamics, at extremely high current, energy, and plasma densities. There is a continuous need to better quantify arc flash hazards, in order to protect workers and promote safer, more effective and efficient workplace practices for electrical equipment installation, maintenance and repair.